Among $\mathrm{H}_2, \mathrm{He}_2^{+}, \mathrm{Li}_2, \mathrm{Be}_2, \mathrm{~B}_2, \mathrm{C}_2, \mathrm{~N}_2, \mathrm{O}_2^{-}$, and $\mathrm{F}_2$, the number of diamagnetic species is (Atomic numbers: $\mathrm{H}=1, \mathrm{He}=2, \mathrm{Li}=3, \mathrm{Be}=4, \mathrm{~B}=5, \mathrm{C}=6, \mathrm{~N}=7, \mathrm{O}=8, \mathrm{~F}=9$ )
→The $IUPAC$ name of the compound is $\begin{array}{*{20}{c}}
{\,\,\,\,\,\,\,\,\,\,Ph} \\
{\,\,\,\,\,\,\,\,|} \\
{C{H_3} - CH - CH - N{H_2}} \\
{\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{C{H_3}\,\,\,\,\,\,\,\,\,\,}
\end{array}$
→